Question

Write a python or java code which can calculate the Shapely-Shubik and Banzhaf indices to determine which state in America has the most power in the primary election.

Answer 1

%matplotlib inline

import powerindex as px

game=px.Game(quota=51,weights=[51,49])

game.calc_banzhaf()

print(game.banzhaf)  

#output   [1.0, 0.0]

game.calc_shapley_shubik()

print(game.shapley_shubik)

#output [1.0, 0.0]

game=px.Game(51,weights=[50,50])

game.calc()

print(game.banzhaf)

print(game.shapley_shubik)

#output [0.5, 0.5]

        [0.5, 0.5]

game=px.Game(4,[3, 2, 1])

game.calc() # again it calculates all available indices

print("Banzhaf index:")

print(game.banzhaf)

print("Shapley-Shubik index:")

print(game.shapley_shubik)

#Output Banzhaf index:

      # [0.6, 0.2, 0.2]

      # Shapley-Shubik index:

      # [0.6666666666666667, 0.16666666666666669, 0.16666666666666669]

countries={"California":4,"Florida":4,"Georgia":4," Louisiana":2,"Michigan":2,"New Jersey":1}

parties=[px.Party(countries[country],country) for country in countries]

game=px.Game(12,parties=parties)

game.calc()

print("Banzhaf index:")

print(game.banzhaf)

print("Shapley-Shubik index:")

print(game.shapley_shubik)

# run this code and you will get this output

      #Banzhaf index:

      # [0.238, 0.238, 0.238, 0.143, 0.143, 0.00]

      # Shapley-Shubik index:

      # [0.233, 0.233, 0.233, 0.150, 0.150, 0.00]